A developing cartridge including a developing roller is known in the art. The developing cartridge is attachable to and detachable from an image forming apparatus.
There is known a developing cartridge including a gear rotatable from a first position to a second position, and a protrusion provided at the gear. The protrusion is movable along with the rotation of the gear, and is configured to be in contact with a lever provided in an image forming apparatus. The lever is moved by the abutment with the protrusion. The image forming apparatus detects the movement of the lever to determine a specification of the developing cartridge. Further, the gear includes a toothless portion. In a state where the toothless portion is brought into facing with a drive gear configured to transmit driving force to the gear, meshing engagement between the gear and the drive gear is released to stop rotation of the gear. Thus, movement of the protrusion is also stopped.